PASylation of IL-1 receptor antagonist (IL-1Ra) retains IL-1 blockade and extends its duration in mouse urate crystal-induced peritonitis

J Biol Chem. 2020 Jan 17;295(3):868-882. doi: 10.1074/jbc.RA119.010340. Epub 2019 Dec 9.


Interleukin-1 (IL-1) is a key mediator of inflammation and immunity. Naturally-occurring IL-1 receptor antagonist (IL-1Ra) binds and blocks the IL-1 receptor-1 (IL-1R1), preventing signaling. Anakinra, a recombinant form of IL-1Ra, is used to treat a spectrum of inflammatory diseases. However, anakinra is rapidly cleared from the body and requires daily administration. To create a longer-lasting alternative, PASylated IL-1Ra (PAS-IL-1Ra) has been generated by in-frame fusion of a long, defined-length, N-terminal Pro/Ala/Ser (PAS) random-coil polypeptide with IL-1Ra. Here, we compared the efficacy of two PAS-IL-1Ra molecules, PAS600-IL-1Ra and PAS800-IL-1Ra (carrying 600 and 800 PAS residues, respectively), with that of anakinra in mice. PAS600-IL-1Ra displayed markedly extended blood plasma levels 3 days post-administration, whereas anakinra was undetectable after 24 h. We also studied PAS600-IL-1Ra and PAS800-IL-1Ra for efficacy in monosodium urate (MSU) crystal-induced peritonitis. 5 days post-administration, PAS800-IL-1Ra significantly reduced leukocyte influx and inflammatory markers in MSU-induced peritonitis, whereas equimolar anakinra administered 24 h before MSU challenge was ineffective. The 6-h pretreatment with equimolar anakinra or PAS800-IL-1Ra before MSU challenge similarly reduced inflammatory markers. In cultured A549 lung carcinoma cells, anakinra, PAS600-IL-1Ra, and PAS800-IL-Ra reduced IL-1α-induced IL-6 and IL-8 levels with comparable potency. In human peripheral blood mononuclear cells, these molecules suppressed Candida albicans-induced production of the cancer-promoting cytokine IL-22. Surface plasmon resonance analyses revealed significant binding between PAS-IL-1Ra and IL-1R1, although with a slightly lower affinity than anakinra. These results validate PAS-IL-1Ra as an active IL-1 antagonist with marked in vivo potency and a significantly extended half-life compared with anakinra.

Keywords: IL-22; PASylation; biotechnology; drug delivery; half-life extension; inflammation; innate immunity; interleukin 1 (IL-1); intrinsically-disordered protein; leukocyte; pharmacokinetics.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biomarkers / chemistry
  • Humans
  • Inflammation / chemically induced
  • Inflammation / genetics
  • Inflammation / pathology
  • Interleukin 1 Receptor Antagonist Protein / chemistry
  • Interleukin 1 Receptor Antagonist Protein / genetics*
  • Interleukin-1 / chemistry
  • Interleukin-1 / genetics*
  • Leukocytes / chemistry
  • Leukocytes / drug effects
  • Mice
  • Peritonitis / chemically induced
  • Peritonitis / genetics*
  • Peritonitis / pathology
  • Uric Acid / chemistry*
  • Uric Acid / toxicity


  • Biomarkers
  • Il1rn protein, mouse
  • Interleukin 1 Receptor Antagonist Protein
  • Interleukin-1
  • Uric Acid

Associated data

  • PDB/1IRA